1. Field of the Invention
The present invention relates generally to a core chip for a magnetic head and a process of fabricating a head core slider using the core chip, and more particularly to a technique for forming a magnetic gap in the core chip so that the depth of the magnetic gap is accurately controlled by grinding the core chip.
2. Discussion of the Prior Art
In the art of rigid or floppy magnetic disk drives (RDD or FDD), there has been used a magnetic head core slider which has a slider body, and a core chip bonded or fixed in the slider body. The core chip has a magnetic gap with a suitable size formed so as to extend across an annular magnetic path which is defined by a coil-winding aperture formed in the core chip. It is noted that the depth dimension as well as the width dimension of the magnetic gap are important factors which affect the operating characteristics of the magnetic head. The depth dimension of the magnetic gap is a dimension between the sliding surface of the core chip for sliding contact with a magnetic recording medium such as a magnetic disk, and an end of the coil-winding aperture, which end is nearest to the sliding surface in the direction perpendicular to the sliding surface. After the core chip is fixed in the slider body, the surface of the core chip in which the magnetic gap is open, and the corresponding surfaces of the slider body are ground so as to obtain the desired or nominal depth dimension of the magnetic gap. Conventionally, however, this grinding operation suffers from various problems, in terms of the accuracy of the depth dimension of the magnetic gap, for example.
In the conventional fabrication of a floppy disk drive (FDD) magnetic head core slider, for instance, the height of the slider body and the depth dimension of the core chip are measured before the core chip is fixed in the slider body. Based on the measured dimensions, the appropriate surfaces of the slider body and the core chip fixed in the slider body are ground so as to establish the nominal depth dimension of the magnetic gap, by estimating or calculating the gap depth dimension from the amount of stock removed by the grinding operation. Therefore, this grinding operation requires the measurement of the depth dimension of the magnetic gap before the core chip is fixed in the slider body, and also requires the calculation of the amount of grinding (estimation of the current gap depth dimension) during the grinding operation. Thus, the conventional method does not permit efficient fabrication of the magnetic head core slider.
In the conventional fabrication of a rigid disk drive (RDD) magnetic head core slider, a core chip is accommodated in a chip-receiving groove formed in a slider body which has a pair of parallel air bearings defined by parallel grooves formed by grinding wheels, for example. The core chip is fixed in the chip-receiving groove with a glass filler, and the air bearing surfaces of the slider body and the corresponding sliding surface of the core chip are ground to obtain the nominal depth dimension of the magnetic gap. The depth dimension of the magnetic gap during the grinding operation is measured through the glass filler, in a direction inclined with respect to the direction of depth of the magnetic gap. Based on the measured gap depth dimension, the grinding operation is performed. However, the in-process measurement of the gap depth dimension in the above-indicated inclined direction requires an optical instrument capable of compensating for a measuring error due to the refractive index of the glass filler, and makes the grinding operation difficult or complicated, whereby the grinding operation tends to be costly and difficult to be performed for accurate control of the depth dimension of the magnetic gap.